Perhaps it needs to be reviewed from a dynamics point of view vs a static?
the pivot point of the hull in the water changes/moves in relation to the moment created by the vertical vector downward.
The horizontal vectors work as a couple with it's moment, and not as dynamic.

a bad example: once the sail breaks the water (decreasing resisting moment,
a lot changing here) it usually rights quickly from that point...
So we are really talking about the moment to break the sail free of the water,
but it seems if you bounce up and down (dynamic loads), sometimes the sail can break free of the water.